M30 running on 3 Cylinders !!! help

[grave77]

I don't know what is it and where!! ... the car starts OK .. nothing wrong ... just when I step on the accelerator reaching over 2000 RPM the engine stops the cylinders 2, 4 and 6 -that's if I'm counting cylinder 1 from the radiator - and it wont work again until I stop the engine and start it again ... this problem started today on the high way. before that there was no problem.

I would like to add a note here. that my alternator doesn't start charging until I rev the engine to above 3000 RPM. I feel that the alternator is noisy or triggering something ... but what is it?! I'm going to try a different DME I just feel that the injectors seas the get the signal.

Any idea guys ?! I'm puzzled !!

[Phatty5BMW]

Maybe the dist. cap and rotor?

[Jeff N.]

ECU problem or injector wiring problem. The motronic batch fires the injectors three at a time. You should be able to match the batch fire sequence to the ECU sequence; if they match I'd suspect the above.

You may also want to check the sensor wire from the #1 plug. That's the trigger for sequencing the firing batches.

BTW, how do you know what cylinders are not firing?

Let us know...curious problem.

[grave77]

well ... when it starts vibrating ( running into 3 cyl mode ) I unplugged the spark plugs HT wire one by one .. the ones were not affected was 2,4,6 that tells that there is no gas. also ... the way the engine behaved when I throttled it took a pattern its like it cuts off then on again and it doesn't sound like a choke stall or something like that.

if it was the sensor that triggers the sequence. I think it shouldn't start correctly then go off sequence right?

I just can't seem to find a logical explanation yet !! but the it behaves has a pattern !!


**EDIT: I just came back from a test, I replaced the DME with an old one .. still got the same problem, I disconnected the trigger sensor ( right plug next to the crank sensor ) and the engine behaved much better, not smooth but seems that the DME used the prediction method. but didn't run in 3cyl mode.

do you think that was it? I reconnected it while engine was running but nothing changed. also gas smell was so obvious and few explosions happened in the exhaust afterwords.

[grave77]

spark is there all the time ... I checked each plug by removing the wire and pluging it back.

[liquidtiger720]

how do you know how many cylinders its running?

[grave77]

from the spark plugs wire. when I removed one by one ... only 3 affected the engine ... and the 2,4,6 cylinders were not affected while spark was alive.

[Jeff N.]

...not lack of fuel problems.

How old are your plug wires? I'm now sort of wondering if you don't have shorts in the plug wires. That can cause intermittant problems.



well ... when it starts vibrating ( running into 3 cyl mode ) I unplugged the spark plugs HT wire one by one .. the ones were not affected was 2,4,6 that tells that there is no gas. also ... the way the engine behaved when I throttled it took a pattern its like it cuts off then on again and it doesn't sound like a choke stall or something like that.

if it was the sensor that triggers the sequence. I think it shouldn't start correctly then go off sequence right?

I just can't seem to find a logical explanation yet !! but the it behaves has a pattern !!


**EDIT: I just came back from a test, I replaced the DME with an old one .. still got the same problem, I disconnected the trigger sensor ( right plug next to the crank sensor ) and the engine behaved much better, not smooth but seems that the DME used the prediction method. but didn't run in 3cyl mode.

do you think that was it? I reconnected it while engine was running but nothing changed. also gas smell was so obvious and few explosions happened in the exhaust afterwords.

[grave77]

Jeff, in that case why would 2, 4 and 6 get affected, and why would if start normal then F-up when reving it? I removed the spark plugs and they look acceptable.

Does the DME detect poor spark? or bad wires?

[grave77]

I went to the scrapyard today and got the sensor with the spark plug wire. but it didnt help up. I'm going crazy !!

today it was cold in the morning ... I started the engine and it idled just fine.

when it warmed up I reved it and it got back to the problem ...

[SRR2]

Before going any farther with the ECU, you should fix the alternator. You know something's wrong there and depending on the nature of the failure it's possible that it could be screwing up the ECU.

Also check the crank position sensor. They are known problems -- they loosen up, move away from the phonic wheel, and leak oil. It's tricky to get to, check your Bentley for instructions.

[grave77]

the crank sensor is new .. I had it screwed up before ... the alternator was faulty but the car was working without a problem before. I'm thinking of a full reset. whould this help?

[SRR2]

If the electrical system is having problems, you can't necessarily depend on any systems that depend on it. I've been an electrical/electronics engineer for a LONG time (in aircraft and automotive instrumentation and power systems), and one of the principles that has served me very well over the years in making nonworking things work is this: "Fix what you know is broken." IOW, if you have a system with multiple problems, any of which are of unknown origin, you first fix the problems you know about, with the knowledge that sometimes (but not all the time) the unknown problems are dependent on the known one/s.

To put it another way, it's doubly difficult to troubleshoot a problem when you are dealing with a known problematic associated system. In your case you are having engine management problems. The ECU and related systems heavily depend on a good source of DC power, yet at the same time you know that your alternator is having some kind of problem. Ergo, FIX THE DAMN ALTERNATOR!!! 8-)

It probably wouldn't hurt to pull the connector off the ECU to reset it. I think this is much easier than disconecting the battery because all other systems (radio, trip computer) keep their power. The ECU is easy to reach. It's in a box on the right side of the firewall, right in front of the windshield. The ECU is the module closest to the windshield. The connector comes off by unhooking the bail and pulling it up. Keep it off for a minute, then reconnect and give it a try.

[Bellicose Right Winger]

With fuel smell, it sound like ignition to me also. Pull and inspect distributor cap & rotor. Cyl's 6, 2 and 4 are sequential in the 1-5-3-6-2-4 firing order. Look for carbon tracks.

Pull a plug from 2,4 or 6 after running engine. Wet plug means ingnition problem, dry plug means fuel problem.

Injectors 2,4,6 are energized simultaneously. Pull off rubber boot from an affected cylinder and backprobe connector with DMM. Other DMM lead goes to engine. With engine running, should measure 12V continuously on one pin. The other will read less then 12V, as DME completes circuit to ground.

Paul Shovestul



...not lack of fuel problems.

[grave77]

i already tried another ECU i have as a spare, didn't help up. i'll fix the alternator and see.

i'll keep u posted ..thanks a lot

[grave77]

plugs were dry, black as the AFM is not very good. the gas smell was when i disconnected the cylinder identification sensor.

i'll do the DMM check today i'll see the signal with a portable oscillascope (the wire to DME)

thanks mate :)

[genphreak]

I don't know what is it and where!! ... the car starts OK .. nothing wrong ... just when I step on the accelerator reaching over 2000 RPM the engine stops the cylinders 2, 4 and 6 -that's if I'm counting cylinder 1 from the radiator - and it wont work again until I stop the engine and start it again ... this problem started today on the high way. before that there was no problem.

I would like to add a note here. that my alternator doesn't start charging until I rev the engine to above 3000 RPM. I feel that the alternator is noisy or triggering something ... but what is it?! I'm going to try a different DME I just feel that the injectors seas the get the signal.

Any idea guys ?! I'm puzzled !! I know its a sore point, but I know that traditionally alternators die at high rpm. I think in many cases they are closely matched to the speed range of the motor for efficiency reasons. My experience with older Fords proved this many times (all of mine had Bosch (but certainly not BMW spec) alternators)

It'd be interesting to know how they are rated by the manufacturers in this respect, ie- is a 540 alternator the same or is it a bit better at higher rpms? (assuming M60s have higher rev limits than M30s)... it'd help us know what to do if we start increasing the rev range of our motors (for the keener ones amongst us...) :) Nick

[Bill R.]

cylinders, ie you checked it with a noid light and saw the injectors were pulsing then it sounds like ignition.. and the fact that its three sequential cylinders on the dist cap also sounds suspicious, i would also pull the dist cap and rotor first and see if somehow the dist cap is off center, perhaps a poorly made one that isn't centered exactly on the dist or if the rotor and cap contacts are extremely worn so that the gap is much greater on one half of the dist rotor to cap as it turns which would cause it to need much more energy to jump the gap under load or at higher rpms.... does it only miss at higher rpms under load as your accelerating or does it continue to miss even when your cruising at one steady speed with the rpms above 2k?





With fuel smell, it sound like ignition to me also. Pull and inspect distributor cap & rotor. Cyl's 6, 2 and 4 are sequential in the 1-5-3-6-2-4 firing order. Look for carbon tracks.

Pull a plug from 2,4 or 6 after running engine. Wet plug means ingnition problem, dry plug means fuel problem.

Injectors 2,4,6 are energized simultaneously. Pull off rubber boot from an affected cylinder and backprobe connector with DMM. Other DMM lead goes to engine. With engine running, should measure 12V continuously on one pin. The other will read less then 12V, as DME completes circuit to ground.

Paul Shovestul

[grave77]

well ... when the car starts everything is fine ... after I rev it over 2K it starts to vibrate telling me that its running on 3 cylinders. the spark is reaching to the plugs as when I pulled the plug wires I saw the spark jumping to the spark plugs but the engine did not change its behavor only cylinder 1, 3, 5 did change when I pulled the plugs wire. I would say that a bad distributor will make the engine skip one spark or two but not all the time.

when I switch the engine off and on again it returns with all the cylilnders on until I rev it over 2K again to run in 3 cylinders.

Does the ECU detect bad injectors? or my alternator is charging with crappy current that affects the ECU badly?! anyway I got an alternator used to be for my dads E32 ... I will install it tomorrow and see.

[grave77]

that's something else Nick ... what I need now is to make the engine rev back to acceptable limit mate !! ...

but if I wanna talk about the alternator, M30 alternators are noisy ... actually they are the most noisy alternators I experienced. I felt that when I installed my audio system, so if there are more quiet alternators that would be an upgrade. but I don't recommend more power since it's already 140A ... more current will kill the battery.

[genphreak]

that's something else Nick ... what I need now is to make the engine rev back to acceptable limit mate !! ...

but if I wanna talk about the alternator, M30 alternators are noisy ... actually they are the most noisy alternators I experienced. I felt that when I installed my audio system, so if there are more quiet alternators that would be an upgrade. but I don't recommend more power since it's already 140A ... more current will kill the battery.Is an M5 alternator the same item? I was only guessing that the 540i one would swap in. Perhaps an e39 or e38 one even, the newer the model the better the alternator. Knowing your ability to access parts these might be good options bud! Have a good weekend, let us all know what happens :) Nick

[grave77]

I installed my dads E32 alternator ... it was exactly the same on mine. I suppose that u can use the 540 alternators .. I just need to double check in the scrap and compare.

[grave77]

well .. I replaced the Alternator, dist. and rotor. and new HT wires. I still have the same problem.
I tired to investigate a bit further, what's going on is that the alternator is not getting the field power until the engine is reved over 2k, seems that the enigne is running in 3 cyliners when this current reaches the alternator to start charging. I started the engine again and didnt rev it as to keep it running normal. I connected the field bolt to 12V source and the engine started running in 3 cylinders again.

I seem to have a deep electrical problem, therefore I would start were that alternator should get the field current, it should be a relay somewhere. but what is signaling the DME to stop the cylinders. !!

[Bill R.]

fuel to some injectors possibly the cylinders that aren't working for you. Does the eat chip that you have have the rev limiter still in it? If so your voltage problem could be causing trouble with the eat chip and that may be the limiter kicking in at 2k... If you still have the original chip you might try that. But this is all dependent on your being a fuel problem rather than a spark problem. If you have some kind of a huge current draw that too could cause a missing problem but i think it would be random rather than 3 cylinders in a row on the firing order. If your driving a car that has a bad alternator and your driving on battery only as it gets weaker the first things that happen are that the abs light and the airbag lights come on when voltage drops below a certain level and then the engine starts running poorly just before it quits when the battery is too low. The injectors draw a fairly large amount of current, so they are one of the first things affected when battery voltage gets low..




well .. I replaced the Alternator, dist. and rotor. and new HT wires. I still have the same problem.
I tired to investigate a bit further, what's going on is that the alternator is not getting the field power until the engine is reved over 2k, seems that the enigne is running in 3 cyliners when this current reaches the alternator to start charging. I started the engine again and didnt rev it as to keep it running normal. I connected the field bolt to 12V source and the engine started running in 3 cylinders again.

I seem to have a deep electrical problem, therefore I would start were that alternator should get the field current, it should be a relay somewhere. but what is signaling the DME to stop the cylinders. !!

[grave77]

well ... today after I installed the alternator, the car wouldn't start as the battery was low, I jump started it from another car, and when I disconnected the cables it ran poorly just like you mentioned when I reved the engine with the cables still connected to the other car it went into 3 cylinders.

I'm sure it't not a voltage drop but I would guess that there is a signal or something messing up the DME.

one thing I was thinking about, does the Transmission error trigger something like that? as you know I changed the transmisson to manual and didn't short the pins that make it shut up ! ..

but it's been running like that for a long time and I also know that this error makes the auto run the 3rd speed only. so it shouldn't go to the engine.

one other thing I remember was that when I did the last oil change, the OBC wasn't resetting, I don't know if this has to do anything with it too.

[Scott H]

did you gap it properly? has it moved on you? have you tested the coil resistance and voltage values?

the new alternator has a new voltage regulator in it?

just trying to thing of other things to check

[Rustam]

well ... today after I installed the alternator, the car wouldn't start as the battery was low, I jump started it from another car, and when I disconnected the cables it ran poorly just like you mentioned when I reved the engine with the cables still connected to the other car it went into 3 cylinders.

I'm sure it't not a voltage drop but I would guess that there is a signal or something messing up the DME.

one thing I was thinking about, does the Transmission error trigger something like that? as you know I changed the transmisson to manual and didn't short the pins that make it shut up ! ..

but it's been running like that for a long time and I also know that this error makes the auto run the 3rd speed only. so it shouldn't go to the engine.

one other thing I remember was that when I did the last oil change, the OBC wasn't resetting, I don't know if this has to do anything with it too.

Have you used a multimeter to check connection of injectors 2, 4 and 6 with ECU connector? They are connected together as do 1,5 and 3, yet all have common connection on other end with purge valve and relays.

[grave77]

I didn't check the crank sensor ... but I remember that it only takes one position right?
I didn't reach to the injectors yet as I need to remove the AFM and its hoses too. and it was a bit dark today so I was going to do so tomorrow.

what resistance should the multimeter read on an injector?

[grave77]

since the car starts ok ... then messes up after reving it I don't think it's a connection problem, right?

[Rustam]

I didn't check the crank sensor ... but I remember that it only takes one position right?
I didn't reach to the injectors yet as I need to remove the AFM and its hoses too. and it was a bit dark today so I was going to do so tomorrow.

what resistance should the multimeter read on an injector?


Resistance of the injector maybe between 10 and 20 Ohm. Checking injectors for their resistance is unnecessary as we don't suspect them to be faulty since they do inject before 2000RPM. But you want to check the wires connecting to the injectors...

The multimeter reads ZERO resistance when its connected to good wire, showing that there is presence of connection between multimeter leads. Mind that it has to be zero - not infinity. Check for presence of this resistance from every one of those injectors to the ECU while moving neighboring wires 2,4,6 - pin 17 of the ECU 1,3,5 - pin 16 of the ECU...

I would check every one of available connections to ECU in this fashion to make sure that there are no short circuits at all. Have you got wiring schematics?

Since the car starts and revs up to 2000 RPM the problem may be a connection to something that starts acting differently at 2000 RPM!

Fool-proof procedure for finding what's wrong would be to tabulate currnets along all connections to ECU while the engine is running below 2000 RPM and then tabulate all those currents while the engine is running above 2000 RPM. Then see what has changed. Time consuming - yes, but fool-proof.

The problem is obviously electrical and connections are at stake. If all the connections are ok suspect the ECU. If you are ready to open it and start checking it for problems you may want to take a look into this link:

http://frwilk.com/944dme/

He provides electrical schematics for Bosch Motronic 1.3


Set your head at ease by checking all the connections to ECU for short circuits before and after the car has run on 3 cylinders... If they are all well - you've eliminated one possibility - less room for going crazy...

[grave77]

well I'm 100% sure of the ECU as I replaced it with one I keep at home. that was the first test I made. I installed the OEM chip but the battery is dead now and I had no time to jump start it.

fool-proof test would be an option if the OEM chip didnt fix the problem. but I was going to ask would a bad injector coil call the ECU?

also I wan't to know which relay triggers the "alternator magnatic field" terminal?

I feel that there is some relationship ... since when I manually trigger it the engine runs into 3 cylinders, so it's not the 2K rpm limit, its the magnatic field terminal that starts when I rev over 2K RPM.

[Rustam]

fool-proof test would be an option if the OEM chip didnt fix the problem. but I was going to ask would a bad injector coil call the ECU?

also I wan't to know which relay triggers the "alternator magnatic field" terminal?

I feel that there is some relationship ... since when I manually trigger it the engine runs into 3 cylinders, so it's not the 2K rpm limit, its the magnatic field terminal that starts when I rev over 2K RPM.

So I take it at this point you have not checked electrical connections with ECU?

I'm sorry - I dont know what you mean when you mention a relay that triggers "alternator magnetic" field... In theory there is no reason to turn on magnwetic field of the laternator since its used as a generator not as electric motor. If we expected to have it turn on its own by application of electricity we would have something to trigger its magnetic field... So I am quite puzzled by your message there...

There is one relay that I can see here in schematics that participates in transfer of electricity from alternator - unloader relay... Unloader relay is located in front power distribution box - right before the windshield on driver's side...

You must provide a bit more detail on what you do and what you do it with... For instance I have hard time understanding the meaning "i trigger it" - what do you trigger? and how do you perform this triggering process?

The alternator has only two terminals - for provision of electric potential - they have nothing to do with triggering magnetic fields. Perhaps you meat a "starter" instead of "alternator"? The terminal being the one on the solenoid which does use magnetic field to push starter gear???????

The "starter relay" engages magnetic field of the starter solenoid. It is located in same box as the unloader relay mentioned above. Looking from driver's side towards passenger's the relay is second from left right by the file of fuses...

I'm very puzzled by this post

Now regarding bad injector coil - Its possible that bad injector coil like everything else being observed by ECU would provide you with some message. Now question is - is it possible to have bad injector coil under your circumstances? Rather unlikely - the coils are inside stamped body unable to be accessed by any moving body, and made to withstand vibration! So chances of having the coil connection "slip" are next to impossible. Of course the coil can burn out technically speaking - but how much electricity does your ECU have to provide for that? Much more than it is capable of...

You should check all the connections to ECU for short circuits as I mentioned - that shall be your first step.

[grave77]

the alternator doest have permanent magnatic field, the small bolt gets current from the battery to generate magnatic field to make the alternator charge. and yes not turn. i tested it on the bench.

when this terminal gets power the alternator starts charging and my engine runs in 3. hope this clears what i mentioned before.

[grave77]

I have installed back the OEM chip, car stopped running in 3 cylinder mode, and the problem is precisely in the alternator circuit.

as I mentioned before explaining the magnetic field of the alternator which is connected to the smaller bolt on the alternator, the power to this terminal is disconnecting and reconnecting again making the ECU to restart or cut off and back on again ... also the dash ( OBC ) is alerting me again every time this happens with the ABS light flashing.

that's why I asked about the other terminal with the thin wire connected to the alternator. ( I called the magnetic field terminal ) since the other is the battery cable.

[Javier]

Test voltage at pin 12 of diagnostic connector (it is tied to the small bolt you said you used to trigger the alternator magnetic field). It should read about 0 volts wile the battery light is on, and quickly climb to about 12 volts when engine starts.

Pull out the unloader relay and test the engine, let us know if any thing changes.


Javier

[Javier]

Here is the charging diagram for your car that will let you understand why is it lighting ABS when alternator has issues. (zippd due to size).

I feel you have issues either with the unloader relay or the battery light, not the alternator.

Javier

[grave77]

well there was a red light with a " ! " mark that was glowing on and off along with the ABS light. can you tell me more about the unloader relay and its location?

Thanks Javier ... :)

[pink-planet]

i was just following the thread and reading, and I was wondering why you have such a problem with your car, isn't a car a machine where you check all the cables if they are connected to the right place? Maybe am wrong, a nice explanation will be good. thanks

[grave77]

ok ... I think now I'm getting to something ... but I have to ask something, does the RPM have anything to do with this relay?

where is the instrument cluster and the unloader relay located?

thanks mate your really helping me here !!

[grave77]

not always mate, when a machine has a controller in the middle that makes the machine behave different due to something else you don't know, here you need experience. that's why every one here ask questions in the forum.
that will also help other who might face this problem ( same machine different place )

[Javier]

then you have to have turned on a red light with a battery icon. As you may see from the charging circuit drawing, the unloader relay has a diode that feeds the alternator rotor for start up (wile the residual magnetism isn't enough to generate something). If this diode is opened (damaged), then you will nave the described symptoms, and the battery light will not go on.

Yes I would check the unloader relay, as it may be the key to your alternator issues.

See this threads for help:

http://www.bimmer.info/forum/showthread.php?t=10435

http://www.bimmer.info/forum/showthread.php?t=8970

Javier

[pink-planet]

I still don't get it, it's something with certain input and certain output, and the people who developed the car should have thought of all the possibilities, which may cause problems and how to fix them, didn't they?! Anyway, wish you solve your problem with your car as soon as possible.

[grave77]

thanks mate, it's starting to reveal the reason one test i have to report back to Javier and i think i would know whats wrong.

[Rustam]

thanks mate, it's starting to reveal the reason one test i have to report back to Javier and i think i would know whats wrong.

GRAVE I have mentioned location of unloader relay in my post back to you (and spent good time typing too) - that relay is located in electronic box on the left side of the engine compartment, right before the windshield...
generically, UNLOADER RELAY is third one from left in the row next to FUSE FILE...

AND I agree with Javier - based on what you said - the only relay that participates in transfer of electricity with the alternator is unloader relay

Now JAVIER - regarding the diode - Bentley's manual for e34 says that the diode is only used in M5. Can you comment on this?

[grave77]

thanks mate, but I don't remeber you mentioning the unloader relay, you were totaly against it. still I'm going to do that today. I hope this is where my problem is ... my car is in the parking since last week ... I'm driving a Honda Civic now ... I can't wait to drive my bimmer again ... crossing fingers.

[grave77]

those 2 threads r gr8 !! .. I'm hoping it's not a cable problem as when they replaced my transmission to manual they were messy so I hope no wires been disconnected. I'll check it today when am back home.

thanks Javier ... :)

[Javier]

but unloader relay is shown in the drawings with a diode inside the relay.

See picture

http://www.bimmer.info/forum/attachment.php?attachmentid=727&stc=1&d=1105812969

Javier

[grave77]

ok ... I extracted the unloader relay and tested the diode with an AVO meter ... test was OK, terminals r clean. so I need to test the other diode, that's if it exists in my car.

I also went down and grounded pin number 4 and the light glowed.

when I tested the field connector on the alternator, the power is not getting there until I throttle the engine.

I checked both fuses 17, 28 they r ok, I think the uncoupling diode is open.

some strange signal was on the diagnostic connector Pin 13 .. its signal was rough and the engine was rough just the same as it was on this pin.

this is all what I found. ...

[Javier]

Let's test continuity from pin 9 of relay socket (corresponding to pin 85 in relay) to pin ** 12 ** on diagnostic connector (http://www.unofficialbmw.com/e36/electrical/e36_reset_service_lights.html), should have ~0 ohm reading.

If OK, also test continuity from said pin 12 and the terminal D+ at the alternator (the small live connection), also should get about 0 ohm reading.

With the ** engine off **, and key in run position, if you ground pin 12 at diagnostic connector (or terminal D+ at the alternator), battery warning light should go on. This will also verify continuity.

Edit: May be your mechanic unpluged X6508 and never put it back!! See picture.

Javier

[grave77]

Thanks mate, I will check this for sure, I have unpluged this cable when I removed the head, maybe the wires were dry and caused some disconnection. I will inform you soon :)

[grave77]

I grounded pin 12, battery light glowed. seems it's the plug X6200 miss connection or the connection wire cut somewhere in between.

What's the Evaporative Purge Valve for?

[Rustam]

I grounded pin 12, battery light glowed. seems it's the plug X6200 miss connection or the connection wire cut somewhere in between.

What's the Evaporative Purge Valve for?

to let fuel fumes into the engine.
BTW have you found my reply to your message on m30 head rebuild?

[grave77]

yeh, using the tool u have in the signature picture, right.

well i did the head and learned a lot too, i'm gona do the valves clearance just when i fix the missfire problem. as with the oem chip its no longer running in 3 cyl. but some cylinders r not firing all the time. and with every time that happens OBC resets and shows errors on the screen.

now when i rev the engine it totally missfires for a glimpse then continues ... if i did it again it bangs in the exhaust.

i'm suspecting a very bad spark plug that's wasting the spark energy.

still it has a pattern when it totally misses firing ** the the engine goes off then on again then OBC restarts with the error messeges, also red engine check light glows for an instance.

now i can admit that lots of raw gas is emitted.
i need some more tips about this missfiring issue.

[Javier]

short/open circuit bringing down the power. This momentary low voltage may trigger all sort of gremlins in the car electronics.

Think you have to check all the connections that were manipulated recently, also battery connections, fuses and alternator connections.

I would stick an analog voltmeter or a light bulb on pin 14 of the Diagnostic connector "Battery voltage to main engine components" and observe for flickers or momentary voltage depressions.


Javier

[grave77]

I did that already Javier, I observed the analog meter on the main battery bolt next to the heater valves, the only wierd reading was the HT-coil, pin 13 on diagnostice connector. the DME is cutting off the signal when I full throttle, just after it starts to speed the RPM coil signal stops then continues. I have called Mark.D few days ago, he told me that there is a pin on the DME that detects voltage level, would this matter? what pin would it be?

[Javier]

the engine wiring, as they are evident from the alternator malfunction. You did grounded pin 12 but not D+ in the alternator, isn't it? what are you waiting to fix definitely the charging system? there should be a wire from pin 12 to D+ trough the said X6508 connector. Did you find out what is going on? I'm more scare of where did the wire was connected to if not connected in the battery light circuit. Are we sending a +12 Vdc signal somewhere else when alternator kicks in? where to?

You received a god advise in this thread, fix whatever you know is not working first, then go for the unknown.

DME receives voltage signals at pins 27 (key on), 18(power feed), 37 (DME Relay on), 38 (anti-theft). Would check DME relay first.

Javier

[Rustam]

I did that already Javier, I observed the analog meter on the main battery bolt next to the heater valves, the only wierd reading was the HT-coil, pin 13 on diagnostice connector. the DME is cutting off the signal when I full throttle, just after it starts to speed the RPM coil signal stops then continues. I have called Mark.D few days ago, he told me that there is a pin on the DME that detects voltage level, would this matter? what pin would it be?

ok - I am not sure that I am following this closely, but have you checked the order of the ignition wires at all? I recall I connected them wrongly and the engine still run - haphazardly

[grave77]

I don't remember removing them to reconnect them in a wrong way. but I would make use of some information, from the dist to the engine wiring order. also the problem started suddenly while driving so there is something that failed and started this problem. I will go fix the alternator problem now, I was sick the few days ago, I also bought new spark plugs as I'm suspecting a bad plug causing the HT level to drop, just an assumption.

I will also check all the connections including the DME relay. I will inform you as soon as I get something ...

I really appreciate your help guys ...

[genphreak]

I don't remember removing them to reconnect them in a wrong way. but I would make use of some information, from the dist to the engine wiring order. also the problem started suddenly while driving so there is something that failed and started this problem. I will go fix the alternator problem now, I was sick the few days ago, I also bought new spark plugs as I'm suspecting a bad plug causing the HT level to drop, just an assumption.

I will also check all the connections including the DME relay. I will inform you as soon as I get something ...

I really appreciate your help guys ...Stock leads are numbered on the cable, and the distribtuor cap is numbered as well (at least it is on all my Bosch ones) and cyl 1 is at the front of course...

btw, on my car when the fan belt blew stopping my alternator running properly the battery died and the ABS light came on after the last start. The battery voltage bulb never did, so with my cluster out this week it is time to check it. I only knew cos I saw the temp gauge move up a tad the ABS light on and the headlights dim; after popping the hood I saw what the battery light didn't show; the fanbelt shredded almost completely. Was only a month old, bought from the stealer too. Replaced again that night with a spare and next day with the right one, all was then good...

[grave77]

Well .... I fixed the alternator problem, it was from the Plug, it was rusty. but I still have the engine problem. I check every connection from DME to engine nothing was wrong. I realized that the idle regulator valve was acting funny too, it flaps on and off when I throttle the engine ... thats why its stopping and resuming when I throttle it. but I'm sure it's the DME that is getting some silly signal to give such signals to other engine components. I also checked the DME relay .. it was ok .. but sadly I think I caused a problem with the contoller that switches the DME relay on, now the engine remains running even with the ACC switch off.

[Javier]

If DME relay remains energized no mater key off, then DME should be damaged, probably, output transistor to DME relay (DME pin 36). (or DME relay contacts seized, of course, doubt it though).

In this page posted by Shogun some time ago, http://www.e34.de/frames.php, after the link "Schrauberecke", after the link "Tips und Tricks", after the link "Schaltplan der Motronic" is a drawing of DME 1.3, it shows the internals of DME. Don't know if you should mess with it, but some one knowledgeable in electronics with the drawing may help you debug it.

I think, and do not quote me on this, that what you refer about the Idle control does not mean it is not working. Idle control is there to automatically adjust idle wile throttle is closed. Guess it closes when you throttle up.

Originally, you referred that 3 cylinder issue starts when alternator kicks in, is now permanently (as your alternator is always in). If it is, revealing a change on the issue on the new alternator condition, have you tried to disconnect the alternator and check for 3 cylinder operation? Just curiosity to establish a link, if it is there.

Javier

[grave77]

ok ... seems it was solved now. I was fed up and I took it to a workshop close by, while driving there the car was fine no missfiring no 3cyl thingy ...
next day they called me and told me that the injectors was really bad. and they were behind the problem. DME was ok I still didn't know what they did to fix the ACC switch. my only interpritaton was that the injectors were drawing higher current when the alternator was on that causes the DME to stop the signal, can this be it?

I will get the car today and I hope that this was my problem ... so it would be added to the forums archive.

I'll keep you posted when I get it back.

[pink-planet]

Congratulation on solving your car problem, hope that it will run now smoothly without any problems:)

[grave77]

well I took it on a ride today ... ran smooth ... still on OEM Chip ... I will restore the EAT soon. but they installed me single hole injectors instead of my old 3 hole type. they said they are newer or like the E38, E39 injectors. I also replaced the AFM and vacuum hoses too. tomorrow I will have a long trip for a better test.

[Rustam]

ok ... seems it was solved now. I was fed up and I took it to a workshop close by, while driving there the car was fine no missfiring no 3cyl thingy ...
next day they called me and told me that the injectors was really bad. and they were behind the problem. DME was ok I still didn't know what they did to fix the ACC switch. my only interpritaton was that the injectors were drawing higher current when the alternator was on that causes the DME to stop the signal, can this be it?

I will get the car today and I hope that this was my problem ... so it would be added to the forums archive.

I'll keep you posted when I get it back.

I would ask them to tell me what exactly the problem was, before paying the money...

[grave77]

well as I said, they replaced the injectors, I got the old ones. the electrican said that there was a short circuit in the fuse box, that caused the ECU relay to stay on. this one I caused it by mistake since one of the fuses burnt and I used a thin wire to replace it and that wire was connected to the one next to it.

tomorrow I will test the injectors on an external power supply with an accurate Ameter.

I took a garuntee incase things went wrong.

The main problem is that MarkD wasn't able to trace the Chip code and tell weither there was a routine that makes the ECU run like that on a certain error or not. but today was the longest trip I made since it started. and I had no problem. tomorrow is the biggest prof. I have a 100M trip, am sure it would tell.

Thanks for you all assisting me in this especially you and Javier, I think I leared hell out of it.